The present invention relates to a device for influencing the composition of the operating mixture that is supplied to an internal combustion engine according to a process wherein the gaseous media are supplied via a metering cross section which is variable proportionately to the adjustment of a mixture quantity control member, the proportionality of which is adapted to be influenced multiplicatively between the factor 0 and 1 by a regulating device which determines the operating condition of the internal combustion engine and further comprises a throttle member for determining the metering flow cross section disposed in a line that discharges into the induction tube and a sensing device for transmitting the adjustment of the mixture quantity control device to the throttle member.
In known processes the composition of the fuel-air mixture is influenced by metering a corresponding amount of fuel to the amount of air drawn in by the internal combustion engine. This has the advantage that fuel metering can be controlled much more readily than air metering in that the quantity of fuel introduced tends to be far less influenced by the pressure and temperature. In internal combustion engines whose fuel-air mixture is to be adjusted to specific .lambda. values, the dependence of the torque obtained on the amount of fuel introduced is particularly affected when a weak operating mixture and an air value of .lambda. .gtoreq. 1 are used as in this case the torque change relative to the change in the air value .lambda. is especially marked. Modes of operation employing .lambda. .gtoreq. 1 values are especially advantageous from the point of view of fuel consumption but in this range the above disadvantage affects various modes of control, for example, even when using the idling of the motor as a regulating parameter as fresh torque fluctuations are produced when changing the fuel supply regulated by the idling of the internal combustion engine.
A process has already been proposed wherein the composition of the additional air is dependent on the adjustment of the mixture quantity control member and this dependence is adapted to be influenced multiplicatively between 0 and 1 by a control device determining parameters of the internal combustion engine.
It is also known to influence the fuel-air mixture by supplying additional air but in the known solutions this is carried out either directly as a function of the operating parameters or as a direct function of the main throttle valve (butterfly valve) position in the induction tube. The supplying of additional air to an operating mixture of specific composition which was produced, for example, by a carburetor, has the special advantage--particularly when the mixture is regulated according to the engine idling--that in the lean operating range the change in the amount of air supplied to the mixture compared to the change in the amount of fuel supplied to the mixture produces substantially smaller torque changes and the adjustment/control is not adversely affected by excessive torque fluctuations. Control by additional air is also substantially faster owing to the reduced inertia of the air and because, with this form of metering, the delays, i.e., dead periods, in the control circuit are not as great as with control of the fuel quantity. Moreover, control by the proposed method is rendered substantially more rapid and accurate by a rough influencing operation carried out before the actual control operation, this rough influencing corresponding to the adjustment of the mixture quantity control device with additional multiplicative processing of the transmission between the control device and metering of the additional air.